Helixoidal combined ore-roasting furnace and cooling-hearth.



E. A. CLARK & W. H. DAVIS. HELIXOIDAL COMBINED ORE ROASTING FURNACE ANDCOOLING HEARTH.

APPLICATION FILED SEPT. 27, 1910.

Patented June 18, 1912.

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COLUMBIA PLANOCIRAPH E. A. CLARK & H. DAVIS. HELIXOIDAL comma!) 01mROASTING PURNAOE AND GOOLING HBARTH.

APPLICATION FILED SEPT. 27, 1910. 1,029,667, r Patented June 18, 1912.

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WMMOM COLUMBIA PLANDGRAPH co.,wASHlNGTON, n. c.

economical features of almost equal importance, such astheconsumptionofcyanid,

STA PATENT FF "ELLSWORTI-I A. CLARK AND WILLIAM H. DAVIS, ,OF BOULDER,COLORADO.

HELIXOIDLAL COMBINED OREBQASTI1\TG FURNACE AND'COOLING-HEARTH.

Specification of LettsrsPatent.

Application filed September 27, .1910.

Patented June 18, 1912. Serial No. 584,104.

To all whom itmcm concern" Be it known that we, ELLSWORTH A.

CLARK and lVILLnur H. Davis, citizens of .the United States, resldlng atBoulder, 1n

the county of Boulder and State of Colorado, have invented .a new anduseful 1mproveinent in Helixoidal Combined Ore- .forsubsequent treatmentby thecyanid process the particulanobject desired is "that the goldandsilver shallbein a condition whereby a ready dissolution of thesemetals-occurs, and correlated with this desireare certain the timenecessary for thedissolution of the *alues, installation andoperatingcosts. In considering the matter of costs it must be rememberedthat theoperating expense is of greater importance than that ofinstallation, since the operatingexpenses are continuous and willfinally amount to much more than that of installation.

It is well known that potassium cyanid, considered as a reagent in theprocess, is an oxidizer. It therefore follows directly that cyanidconsumption will be reduced by oxidation of the one in the roastingfurnace. It is also well known that when tellurium is present, this willbe oxidized .to tellurous oXid, which is a reducer. If the tellurium isin combination with the gold or silver, it follows that, unlesssufficient time is given for sublimation, this tellurous oxid will bedeposited upon the surface of the gold or silver as the case may be. andmicroscopic observation we have found that with a temperature of aboutlive hundred degrees 0. about two hours are required to remove the lastof the tellurium. If the time is less than this incrustations of TeOwill be found on the surface of the gold which will cause the leachingdepartment of the plant to act sluggishly; and if a higher temperatureis used there is danger of forcing the smaller particles of ore beforethe central region of the larger particle is finished. Fusion of thesmaller particle would of course result in incasing such values as werecontained in the particles. An increase in the time limit would alsoincrease in cost of construction and additional cost of operation.Ordinarily with an increase'of the time of the roasting would commercialefficiency.

panying drawings, in which,

By x i a plan view.

of the passage B.

come an increase in the size of the roaster and consequently an increaseof the surface from which radiation can take place. Or with ahighertemperature there would come a greater obstruction of the materialfrom which the roaster is made.

In view of .the above facts we have designeda roasting furnace andcooling hearth with the object in view of regulating the time ofroasting, and the temperature so as to reduce the opcratlng costs to thelowest point, or in other words to produce a-device of this kind whichwould have the greatest The term helixoidal as used herein as definingacontinuous hearth returning to a ,position vertically below theinitialpoint, whatever the traverse of the ore maybe, without regard tothe shape of the roaster, as distinguished from the term hellcoldalwhich might be interpreted as reterrmg t0,a clrcular arrangementonly.

The object of the invention therefore is to obtain a form of roasterwhich will combine .a maximum length of roasting hearth with aminimumamount of ground or floor space covered, thereby securing a device ofthe kind which can .be built more .economr cally than .a largerbuilding, and which will have ,a maximum interior heating surface and aminimum exterior radiating surface, and consequently can .be operatedwith the minimum amount (of fuel.

In carrying out our invention, we lnive lllustrated one form of hearth1n the accom- Figure 1 is a vertical section. Fig. 2 is Fig. 3 is atransverse sect-ion taken u 3011 a horizontal line immediately below thefire grates. Fig. 4 is a detail vertical sect-ion taken through thelower portion of the discharge side of the roaster.

In these drawings, A represents a cylindrical roasting furnace, which isprovided with a continuous spiral helixoidal passage (1 terminating in asimilar but shorter passage b, which latter is a continuation of thefirst passage. The spiral passages a form the roasting furnace and thecontinuation 7) forms the cooling hearth. .A feed hopper B arranged inthe top of the roaster admits the ore to be roasted into the uppermostport-ion A. suitable discharge opening G communicates with the lowestportion of the cooling hearth 6. Suitable vertically arranged shafts Dextend through the various floors of the passages a and 7) and carry attheir upper ends suitable gears e, which are adapted to be driven by anysuitable gear mechanism, not shown. Within said passages are fixed tothese shafts suitable rabbles F. These are designed to be rotated inalternate directions and to act upon the ore so that as it passesthrough the passages it is moved along in a zig-zag manner. Suitablefurnaces G are arranged adjacent the roaster A. and while We have showntwo of these furnaces it will be obvious that this number may be increased, with an increase in size of the roaster. Each furnacecommunicates adja cent its upper end with a passage a, through asuitable flue H, and the heat and products of combustion from thefurnace pass through the passages a and out through a suitable stack H.The lower portion of each furnace, beneath the grate K communicatesthrough an opening J with the cooling hearth b. A suitable air inlet Iis arranged adjacent the discharge opening C and admits cold air intothe hearth portion 7), a part of said air traveling up the passage andcooling the ore by absorbing heat therefrom. The remaining portion ofthe air coming in through the air port I is also heated by thecollecting ore and passes through the openings J and up through the barsof the grate K, thereby supplying heated air to the furnace andefiecting more complete combustion of the fuel. By means of a roastingand cooling hearth combined as herein shown, the objects of ourinvention as previously outlined are carried out, and a considerablesaving in operating costs is made. This saving is due in part to thegreater utilization of the heat units from the furnace, the securing ofperfect combustion by utilizing the cooling of the ore for the purposeof heating air to be admitted to the furnace, and by so arranging thepassages that the ore is moved over a floor of considand lower portions,means for causing ore to travel through said passages, and means foradmitting cold air from the exterior of the structure into the lowerportion of said passage, a part of said cold air passing into thefurnaces".

2. A device of the kind described comprising a structure having acontinuous spiral passage therein, a feed hopper communicating with theupper portion of the passage, the lower end of the passage terminatingin a discharge opening, means for producing an. irregular, zig-zagpassage of ore along the floor of said passage, the lower portion of thepassage forming a cooling hearth, and the upper portion aroastingchamber, the said passage having an opening for the admission of coldair in its lower portion, furnaces arranged adjacent said structure,said furnaces having an opening communicating with the roasting portionof the passage and having an opening in communica-' tion with thecooling hearth portion of said passage, and a suitable stack leadingupwardly from the upper end portion of the passage, as and for thepurpose set forth.

ELLSWORTH A. CLARK. WILLIAM H. DAVIS.

Witnesses GUY A. ADAMS, R. W. LEEOH.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

